In an electrophotographic image forming apparatus, an electrostatic latent image formed on a surface of a photoreceptor is developed with toner by a developing device. The toner with which the electrostatic latent image is developed is stored in a toner cartridge equivalent to a developer storage container, and is sequentially supplied from the toner cartridge to the developing device.
In many cases, the toner cartridge is shaped into a hollow cylinder, and has one end that is closed and the other end near which an outlet is provided. When the toner cartridge is mounted in the image forming apparatus, the toner cartridge is disposed so that the cylindrical section has a horizontal axis. Moreover, when the toner cartridge is driven to rotate on its axis, the stored toner is stirred, and then is conveyed toward the outlet. As a result, the toner is discharged from the outlet in an amount corresponding to the rotation.
In recent years, a large number of toner cartridges have been proposed as a toner cartridge of a full-color multifunctional apparatus from the standpoint of simplicity in handling and recycling.
However, in recent years, toner has been made to include smaller particles for the purpose of higher-quality images. This has caused the toner to have a lower fluidity, and to easily adhere to the inner wall of a toner cartridge. In response to these negative effects, it is necessary to smoothly and stably supply the total amount of toner.
In view of this, Japanese Unexamined Patent Application Publication No. 288875/1991 (Tokukaihei 3-288875; published on Dec. 19, 1991) (hereinafter referred to as “Patent Document 1”) discloses a technique of scraping toner adhering to the inner wall of a toner cartridge, surely stirring the total amount of toner contained in the toner cartridge, and enabling the toner to be discharged. According to this technique, the toner cartridge has a rotatable spiral stirring member provided therein.
Further, Japanese Unexamined Patent Application Publication No. 100074/1992 (Tokukaihei 4-100074; published on Apr. 2, 1992) (hereinafter referred to as “Patent Document 2”) discloses a technique of removing toner from the inner wall of a pipe with vibration so as to prevent the toner from remaining in the inner side of the pipe. According to this technique, a developer container is provided with a blender in which spiral wings wound in opposite directions are respectively provided on the inner and outer sides of the pipe, and a spherical member is provided on the inner side of the pipe.
Japanese Unexamined Patent Application Publication No. 131534/2003 (Tokukai 2003-131534; published on May 9, 2003) (hereinafter referred to as “Patent Document 3”) discloses a technique. According to this technique, a conveyer screw for conveying toner is provided in a residual toner recovery device, and a spherical body for preventing the toner from accumulating is provided on the conveyer screw.
However, according to the techniques of Patent Documents 1 and 2, the stirring member and spiral wings each equivalent to stirring means provided in a toner cartridge have complex structures, and the increase in the number of parts for rotating the stirring member and spiral wings incurs greater costs. The technique of Patent Document 3 causes a similar problem because the conveyer screw for conveying toner has a complex structure. Further, the complex structure of a conveying mechanism causes an increase in the number of parts, thereby causing an increase in size of a toner cartridge. This causes an increase in size of a full-color multifunctional apparatus in which toner cartridges corresponding to four colors Y, M, C, and K are stored. This makes it impossible to satisfy the market need for space saving.